Key points are not available for this paper at this time.
Cholesterol-loaded macrophages secrete cholesterol and apolipoprotein E. The current studies show that this secretion occurs by two independent pathways. In the absence of serum, the cells secrete apolipoprotein E, but not cholesterol. In the presence of monensin (an inhibitor of protein secretion), the cells secrete cholesterol, but little apolipoprotein E. After secretion, apolipoprotein E and cholesterol associate with high-density lipoprotein to form a particle that can deliver cholesterol to the liver by receptor-mediated endocytosis. We conclude that apolipoprotein E does not function to remove cholesterol from macrophages but rather to participate in "reverse cholesterol transport."
Basu et al. (1983) studied this question.